Many high molecular weight condensation polymers can be prepared by utilizing conventional polymerization techniques at elevated temperatures. For example, nylon (66) can be prepared by polycondensing (polymerizing) hexamethylene diamine with adipic acid at a temperature of about 280.degree. C. and polybisphenol A carbonate can be prepared by polycondensing bisphenol A with diphenyl carbonate at a temperature of about 300.degree. C. Condensation polymers of high molecular weight, such as polyesters, polyureas, and polyamides, are generally prepared at temperatures in excess of 200.degree. C. The utilization of high temperatures in such synthesis techniques is, of course, an energy intensive process.
Conventional melt polymerization techniques have not proven to be a viable means of synthesizing polyesteramides. This is because the high polymerization temperatures required of about 250.degree. C. cause degradation of the polymer being synthesized. This is because at the high polymerization temperatures required for the polycondensation reaction, the amine groups present in the diamine being utilized attack the ester-linkage in the polyester amine being synthesized. At the high temperatures required, various other undesirable side reactions can take place. These problems have made the synthesis of polyester amines by conventional melt polymerization techniques at elevated temperatures virtually impossible.
Kitayama, Sanui, and Ogata, "Synthesis of Aromatic Polyesters by Direct Polycondensation with Triphenylphosphine Dichloride", Journal of Polymer Science: Polymer Chemistry Edition, Vol. 22, pages 2705-2712 (1984) discloses the synthesis of high molecular weight aromatic polyesters by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids utilizing triphenylphosphine dichloride as a condensing agent. U.S. Pat. No. 4,668,762 discloses a catalyst system which is particularly useful for the synthesis of condensation polymers, such as aromatic polyesters and polyamides, which is comprised of (1) at least one silicon-phosphorus compound which contains at least one divalent oxygen atom which is bonded directly to a tetravalent silicon atom and a trivalent or pentavalent phosphorus atom: (2) an acid acceptor: and (3) a halogenated organic compound.